Associations of selected atypical non-neuroendocrine cancers with multiple endocrine neoplasia type 1

Abstract Context Multiple endocrine neoplasia type 1 (MEN1) is a hereditary tumor predisposing syndrome, characterized with typical neuroendocrine tumors in parathyroid, pituitary and endocrine pancreas tissues (“3P”). MEN1 is also associated with non-neuroendocrine cancers, which are less studied. Objective To assess the prevalence of certain non-neuroendocrine cancers associated with MEN1 in Finnish patients and compare the findings with a local control population. Design Retrospective registry-based cohort study. Methods 113 MEN1 patients (51 males) treated at Oulu University Hospital between 1982 and 2023 with an average follow-up of 56 patient-years were compared to a local control population (n = 1,045, 520 males, average follow-up of 73 patient-years). Data were analyzed using descriptive statistics, survival curves, and Cox regression models. Results Seven women with MEN1 (11.5%) had breast cancer (BC), seven (6.2%) with papillary thyroid carcinoma (PTC), and five (4.4%) with renal cancers (RC). Mean age at BC diagnosis was 49 years compared to 60 in the general Finnish population. The hazard ratio (HR) for BC in female MEN1 patients was 3.79 (95% CI: 1.66–8.60) compared to controls. Pathogenic variants in established BC risk genes were not present in our MEN1 patients. The HR for PTC and RC were 9.37 (3.59–24.41) and 7.80 (2.74–22.25), respectively. Conclusions This study demonstrates a significantly increased prevalence of BC, PTC and RC in MEN1 patients compared to Finnish general population. The findings support earlier BC screening in women with MEN1 and highlight the need for further research into non-neuroendocrine cancer risks in these patients.